+
+/* The `clearenv' was planned to be added to POSIX.1 but probably
+ never made it. Nevertheless the POSIX.9 standard (POSIX bindings
+ for Fortran 77) requires this function. */
+int
+clearenv (void)
+{
+ LOCK;
+
+ if (__environ == last_environ && __environ != NULL)
+ {
+ /* We allocated this environment so we can free it. */
+ free (__environ);
+ last_environ = NULL;
+ }
+
+ /* Clear the environment pointer removes the whole environment. */
+ __environ = NULL;
+
+ UNLOCK;
+
+ return 0;
+}
+
+#ifdef _LIBC
+static void
+free_mem (void)
+{
+ /* Remove all traces. */
+ clearenv ();
+
+ /* Now remove the search tree. */
+ __tdestroy (known_values, free);
+ known_values = NULL;
+}
+text_set_element (__libc_subfreeres, free_mem);
+
+
+# undef setenv
+# undef clearenv
+weak_alias (__setenv, setenv)
+weak_alias (__clearenv, clearenv)
+#endif
+
+#endif /* _LIBC || !HAVE_SETENV */
+
+/* The rest of this file is called into use when replacing an existing
+ but buggy setenv. Known bugs include failure to diagnose invalid
+ name, and consuming a leading '=' from value. */
+#if HAVE_SETENV
+
+# undef setenv
+# if !HAVE_DECL_SETENV
+extern int setenv (const char *, const char *, int);
+# endif
+# define STREQ(a, b) (strcmp (a, b) == 0)
+
+int
+rpl_setenv (const char *name, const char *value, int replace)
+{
+ int result;
+ if (!name || !*name || strchr (name, '='))
+ {
+ errno = EINVAL;
+ return -1;
+ }
+ /* Call the real setenv even if replace is 0, in case implementation
+ has underlying data to update, such as when environ changes. */
+ result = setenv (name, value, replace);
+ if (result == 0 && replace && *value == '=')
+ {
+ char *tmp = getenv (name);
+ if (!STREQ (tmp, value))
+ {
+ int saved_errno;
+ size_t len = strlen (value);
+ tmp = malloca (len + 2);
+ /* Since leading '=' is eaten, double it up. */
+ *tmp = '=';
+ memcpy (tmp + 1, value, len + 1);
+ result = setenv (name, tmp, replace);
+ saved_errno = errno;
+ freea (tmp);
+ errno = saved_errno;
+ }
+ }
+ return result;
+}
+
+#endif /* HAVE_SETENV */